Conversion
Four scales, one concentration.
Protocols are written in micrograms or milligrams. Syringes are marked in units. Liquids are measured in millilitres. This resolves all four at once.
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The science
Why units are not a measure of drug
01
Units on an insulin syringe measure volume, not mass. One hundred units is always one millilitre, whatever is dissolved in it. How much active compound that contains depends entirely on the concentration of the solution.
02
This is the root of most dosing confusion. A protocol written in micrograms cannot be read directly off a barrel, because the barrel does not know what is in it. Concentration is the bridge between the two scales, and it changes every time you choose a different water volume.
03
The milligram to microgram step is where the most dangerous errors occur. One milligram is one thousand micrograms, so misreading the unit produces a tenfold error in either direction. Confirming which unit your protocol uses before converting is worth the few seconds it takes.
04
Different syringe sizes change the resolution but not the relationship. A 0.5 ml syringe holds 50 units and a 0.3 ml syringe holds 30, with finer graduations in both cases, which makes small doses easier to measure accurately without changing any of the arithmetic.
FAQ
Common questions
How many units is 0.1 ml?
On a U-100 insulin syringe, 1 ml is 100 units, so 0.1 ml is 10 units. This holds regardless of what is in the syringe, because units measure volume rather than mass.
How many mcg is 1 mg?
One milligram is 1,000 micrograms. Confusing the two produces a tenfold dosing error, which is the most common serious mistake in peptide dosing.
Do syringe units mean the same for every drug?
Units on an insulin syringe are a volume scale. A hundred units is always 1 ml. How much active compound that represents depends on the concentration of what you drew.
What is a U-100 syringe?
A syringe calibrated so that 100 units equals 1 millilitre. U-50 and U-30 syringes hold 0.5 ml and 0.3 ml respectively, with finer graduations for small doses.
Why does my protocol use micrograms?
Because many peptides are active at very small quantities. Writing 250 mcg avoids the decimal places that 0.25 mg requires, and decimals are easy to misread.
Does the syringe size change my dose?
No. It changes only how precisely you can measure it. The same 0.1 ml is 10 units on a U-100 syringe and 10 units on a U-50 syringe, but the U-50 has finer marks between them.
VialClock
This page calculates. Your notes app forgets.
Every tool here is stateless by design. What it cannot do is remember that your vial was mixed eleven days ago, or that a step-up is due this week.
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